It has been well known to use hot alkaline cleaning compositions for unclogging drain pipes in sinks, bathtubs and other tub drains from the build-up effect of hair, solidified grease, oils and other debris. For example, U.S. Pat. Nos. 3,489,689 to Tao et al and 3,344,078 to Graham et al teach the use of alkali metal hydroxide in combination with aluminum as effective drain cleaner compositions. However, it is well known that the combination of these two ingredients in the presence of water can lead to evolution of hydrogen gas due to their reaction. Accordingly, various solutions to this problem have been proposed. For example, U.S. Pat. No. 3,537,898 to Fidler proposes a physical separation of the aluminum particles from the caustic alkali metal hydroxide until actual use in the clogged drain. This has not proved to be totally effective.
Other types of drain cleaning compositions involving materials different than aluminum for producing the necessary heat for making such a composition effective as a drain cleaner include those involving the reaction between caustic alkali and a substance which is acidic in nature. For example, U.S. Pat. No. 1,143,295 to McNabb discloses a heat producing composition consisting of a combination of an alkaline substance combined with one or more oxidizing agents such as oxalic acid or a persulfate. It is mentioned that such a composition can be used for heating food products as well as attacking and dissolving solid matter found in drainage and sewer pipes. Also, U.S. Pat. No. 3,791,977 to Ancel et al discloses a dry powder exothermic cleaning composition which contains a base, an acidic agent and optionally various supplemental ingredients including surfactants and chlorine or oxygen-generating compounds as bleaching agents. However, such compositions leave a lot to be desired regarding loss of effectiveness of the active ingredients during storage due to chemical incompatibility of one or more of the ingredients with each other, and additionally resulting from inherent moisture contained in the ingredients.